A theory I've been developing explains this.

When there wasn't enough to go around, capitalism was amazing. It created tremendous wealth, such that for the first time in history, in large parts of the world, there's enough for everyone.

My theory is: Back then, the market for most goods was under-served, so the way the rich got richer was by creating more goods, since you could sell everything you could make (almost always at a profit).

However, in a saturated market, the incentives change; because you can produce far more than you can sell, the rich almost exclusively get richer by taking market share from other players. Making something last 50 years instead of 10 at a 1% cost premium becomes a bad idea, because people care about the headline figure.